Why?

A few weeks ago, I went to an antique show with friends in Lambertville, NJ.  As with most antique shows, there aren't permanent restrooms, but banks of port-a-potties.  When I got to the front of the line, I noticed that one of the booths had the green, "vacant" indicator.  So I thrust open the door and to my horror, there was a female senior citizen with her pants down to her knees, standing and facing the open door with the most horrified, startled look anyone could ever muster.  She said "Oh!" as she looked up and saw me as well as the entire audience of people in line behind me.

Now how women use the port-a-potty is and hopefully will remain a mystery to me.  That said, I cannot conceive of any reason that one would be standing up facing the outside with her pants around her knees AND FAIL TO LOCK THE FRIKKIN' DOOR!  I mean...it's not rocket science.  As I mentally regrouped from the trauma, I came to the conclusion that this was entirely her fault and that it represented a "teachable moment" with the lesson hopefully driven home by the look of sheer terror on my face.  If you're out there, lady, lock the door.